.ts File — TypeScript Source

TypeScript is a strongly-typed superset of JavaScript developed by Microsoft, designed to add static type checking, interfaces, generics, and other features that improve code quality and developer productivity for large-scale applications. TS files contain TypeScript source code that must be compiled (transpiled) to JavaScript before execution. TypeScript's type system catches errors at compile time that would otherwise only surface at runtime in JavaScript, enabling safer refactoring, better tooling support, and self-documenting code through type annotations. TypeScript supports all JavaScript features plus interfaces, enums, generics, union/intersection types, type guards, mapped types, conditional types, and sophisticated type inference. The language has seen explosive adoption since its introduction in 2012 — it is now used by most major tech companies and open-source projects, and is the default language for Angular, increasingly common in React and Vue ecosystems, and widely used for Node.js backend development. TypeScript's configuration is managed through tsconfig.json, and it integrates deeply with modern editors for autocompletion, refactoring, and inline error detection.